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What a submarine is:
It is an underwater vehicle used mostly for military purpose in the current day and age. Civilian uses mostly for science (marine biology)
Cylindrical in shape with conical edges.
Bridge structure called Fin in Europe and Sail in America. Houses periscope and stuff.
Powered by a propeller or pump jet and has fins on the rear to control the level of the submarine. Along with this also uses ballast tanks which are filled with compressed air to ‘surface’ the craft or filled with water to sink it.
Nuclear and Diesel powered: Diesel powered subs require air for the combustion of Diesel engines while nuclear submarines used nuclear energy. This enabled them to remain submerged for a much longer duration under water. Modern-day submarines can stay submerged for over 6 months.
Development started before WWI but accelerated during the war.
Leonardo da Vinci had drawings of a submarine but never materialised into a real craft. It was called a ship to sink another ship. He never revealed it public to prevent wars from turning more deadly than they already are.
Seems like Greeks had mastered the craft back in the 1500s during the reign of Charles V, the Holy Roman Emperor. A couple of guys emerged dry from underwater in river Tagus near the city of Toledo in Spain.
William Bourne, an English mathematician, mentioned in his book about an underwater navigation device. John Napier, Scottish mathematician also mentioned an invention which stayed underwater with divers and could also be used in warfare.
The first real submarine that was built was done in 1620 by Cornelis Drebbel, a Dutchman who worked for King James I of England. It used oars for propulsion.
Interest in submarines went up during the 18th century and there were patents coming up for submarines.
Ballast tank idea was patented in 1747 by Nathaniel Symons using leather bags filled with water. There was a mechanism to remove water from the bags and re-surface the craft. Giovanni Borelli had proposed a similar design earlier.
The first use of a submarine in combat was built in 1775 by David Bushnell and was called Turtle. This was used during the American Revolutionary War for attaching explosives to British Navy vessels anchored in the New York harbour. Although the various attempts at attaching explosives failed, it sparked an interest in using submarines for warfare.
Propulsion of the Turtle was done using hand crank and this meant that the pilot needed to have a great stamina to keep the craft steady. The direction was controlled by a lever that controlled the rudder in the rear of the craft.
The first non-human powered submarine was Plongeur launched in 1963 invented by the French and used compressed air.
Narcis Monturiol launched the first combustion-powered submarine Incitnio II in Barcelona in 1864.
Submarines became effective with the invention of the torpedo by Robert Whitehead in 1866.
English inventor George Garrett and Swedish industrialist Thorsten Nordenfelt built the first steam submarine capable of firing torpedoes called the Nordenfelt I and had a range of 240 km.
Irish inventor John Philip Holland built the Holland Type IV submarine in 1896 which was hybrid using internal combustion engine while on the surface and electric engine while submerged. This class submarine was purchased by US Navy and was used in the Russo-Japanese war in 1905 as well.
World war and the progress made
The development of submarine was accelerated during the world war times where naval warfare was as important as land or air warfare.
U-boats of Germany proved to be deadly in the war.
During the beginning of the war, both England and Germany had submarines though British had significantly more submarines than Germany.
Diesel engined U-boats could have a range of 5000 miles and speed of 15 km/h
During WWI U boats sank over 5000 ships.
During WW2, U boats wrecked British shipping routes.
The US wrecked havoc over capable Japanese Navy.
Pakistani submarine sank INS Khukri, in turn, India sank Ghazi (loaned from the US) submarine of Pakistan.
A submarine has a cigar-shaped hull. This shape helps in drastically reducing the water resistance around the body of the sub.
The sail or the fin might also have a bridge on top which is used for observational purposes.
Propulsion was carried out by humans in the early type of submarines. Before nuclear power was invented, submarines were powered by combustion engines on the surface and electric engines while being submerged.
Earlier crafts used petrol and the later ones started using diesel-electric engines for reduced flammability and increased efficiency. This also meant the batteries could be charged by running the submarine on diesel engines for some time.
Germans tried using a snorkel that could supply oxygen to the engines while being at periscope depth but not without problems of visible exhaust and speed constraints to prevent snorkel from breaking off.
During WWII, submarines designed to carry hydrogen peroxide as oxidisers were built by Germany. Due to limited success, these later carried large batteries instead.
Nuclear energy powers larger submarines in the present day. Nuclear power is used to drive turbines that power the propeller. A disadvantage is the noise generated by coolant pumps whereas a diesel-electric can run on batteries almost quietly.
Ships float over water due to a buoyant force that acts on it. For a submarine to sink below the surface. For this, modern-day submarines use ballast tanks which hold varying amount of water and air.
Apart from using compressed air, submarine also uses tailplanes to move it up and down. There are such planes connected to the Fin (Sail) and body as well.
Forward and Main Ballast Tanks are filled with water to submerge or is filled with air to surface the craft. Depth Control Tanks were used for precise adjustments to the depth. In case of emergency surfacing or submerging, these tanks are used along with these tailplanes simultaneously. But this quick move can make the submarine partially jump from the water as well.
Navigation and communication
Submarines use SONAR sensors that rely on reflected sounds to detect objects. They are located within the hull and sometimes also towed behind the submarine.
Modern submarines use internal guidance systems and depend on global positioning system (GPS) to tackle error in the internal systems. Periscope is used sparingly for short-range observations.
Communication is carried out using low-frequency radio and in short bursts ost of the time to avoid detection.
Since a modern submarine stays submerged for months at a time, oxygen for the crew cannot always be pulled in from the atmosphere. In normal cases, electrolysis of water is used to generate oxygen necessary for the crew to breath.
Carbon Dioxide scrubber is used for removing CO2 from the submarine atmosphere.
Freshwater is produced by using reverse osmosis method which is a method of removing ions, molecules and larger particles by using a semi-permeable material.
About 80 members in a typical craft.
Difficult conditions & maintain radio silence.
Women were allowed only as late as 1985 (Starting with Royal Norwegian Army)
Chakra Class: This is an attack submarine which is under a 10-year lease from Russia since 12 years.
Arihant Class: Ballistic missile submarine which was commissioned in 2016.
Apart from these, there are 14 diesel-electric submarines in use currently.
Kalvari Class (diesel-electric): Attack submarine currently undergoing sea trials.
Submarines are awesome!